Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Tsutomu Hamada

Takafumi Asada

Hideaki Ohno

Katsuo Ishikawa

Shinichi Mizuguchi

Tadayuki Onoda

Kenichi Matsumura

Yasunori Tokunou

Hisato Noda

Hiroaki Saitoh

A hydrodynamic bearing device is provided for use with a spindle motor. The hydrodynamic bearing device has a sleeve made of a sintered metal that is obtained by sintering a sintering material that is iron, an iron alloy, copper, a copper alloy or a mixture thereof. This sintered metal has independent pores, which do not communicate with each other, by selecting conditions for forming a desired sintered body within a predetermined range. The conditions includes a grain size of powdered metal of a material for the sintered metal, a molding pressure when the molded body is formed, sintering temperature and sintering period in the sintering step.

Hydrodynamic bearing device

A hydrodynamic bearing device including a sleeve (), a shaft (), and oil (). With respect to the sleeve (), a stepped portion () provided at one end and an inner peripheral face () extending linearly in the axial direction and continuously with the stepped portion () are formed by a working method that involves the use of a metal mold. The shaft () is inserted so as to be capable of relative rotation with respect to the inner peripheral face () of the sleeve (). The oil fills the space formed between the inner peripheral face of the sleeve and the outer peripheral face of the shaft. Dynamic pressure generation grooves (and), which open in the axial direction at at least one end in the axial direction of the inner peripheral face () and are continuous in the axial direction from one end, are formed in the inner peripheral face.

Hydrodynamic bearing device and spindle motor that makes use of same

A spindle motor including a rotor hub which is rotationally driven by a magnetic action of a rotational magnetic field generated when a current is applied to a wire wound around teeth of a stator core and a magnetic field of a magnet provided on a rotor. Herein, the stator core formed by laminating magnetic steel plates is mounted to an outer periphery of a supporting part of a rotation support shaft of the rotor hub, and the supporting part is made of sintered metal containing a ferromagnetic material. This spindle motor can suppress generation of vibration and noise even when it is reduced in size.

Spindle motor

A hydrodynamic bearing device capable of inhibiting leakage of a working fluid to an outside of a bearing and preventing reduction in radial bearing rigidity, and capable of keeping a gap between a thrust bearing and a radial bearing favorable and rotating stably. The hydrodynamic bearing device includes a shaft relatively rotatably inserted into a bearing hole of a sleeve, a radial bearing surface having dynamic pressure generating grooves formed on at least one of an outer peripheral surface of the shaft and an inner peripheral surface of the sleeve, and a gap filled with a working fluid between the shaft and the sleeve. The shaft is made of high manganese chrome steel or stainless steel, and the sleeve is entirely made of sintered metal of metal particles including at least 60% by weight of iron or copper. Resin, metal or water glass is impregnated in pores on a surface of the sintered metal and cured. Thereby, leakage of the working fluid to the outside of the bearing from the sleeve can be inhibited, and reduction in the pressure inside the bearing can be prevented.

A rotary shaft is inserted in a bearing bore of a sleeve with lubricant stored therebetween. Upper and lower groove patterns, spaced in a vertical direction for cooperatively generating a dynamic pressure when the rotary shaft rotates in the bearing bore, are formed on at least one of an outside surface of the rotary shaft and an inside surface of the bearing bore. The rotary shaft has a recessed portion in a region located between the upper and lower groove patterns for storing the lubricant therein. The recessed portion is asymmetrically tapered so that the lubricant stored in the recessed portion is chiefly circulated to the upper groove pattern against a gravity acting thereon when the rotary shaft rotates in the bearing bore, whereby the upper and lower groove patterns are uniformly lubricated.

Vertical hydrodynamic bearing apparatus

An electrostatic photocopying apparatus has a charger adjacent to a photosensitive body, a retaining means for retaining and supplying image forming particles to the photosensitive body, a particle supply means for supplying the particles to the retaining means, and a single-layer producing means for applying to the image forming particles forces which are not sufficient to remove from the photosensitive body the image forming particles adhered directly to the photosensitive body, but are sufficient to remove the image forming particles attached in the second or higher layer thereover. The image forming particles can be evenly spread in one layer on the photosensitive body. Even if the photosensitive body is carried at high speed, the spreading operation can be carried out correspondingly. In addition, the starting and stopping of the spreading of the image forming particles can be easily performed and the amount of the image forming particles used can be reduced. In one embodiment, the retaining means is a multistylus electrode.

Growing community of inventors

Hirakata, Japan

Tsutomu Hamada